PotenTest is a standardized, hygienically packaged, and reliable stamp test, useful for differentiating organic from psychogenic sexual dysfunction. Fifteen potent control patients wore a PotenTest band on three separate nights, and during a selfinduced erection, while PotenTest reliably induced nocturnal erections and penile rigidity. PotenTest and Snap-Gauge were used to evaluate pre- and postoperative potency in twelve cystectomy patients. The result with each test was essentially the same.